Exploring device for televsion apparatus



June 13, 1933. J.l BAIRD' EXPLORING DEVICE FOR TELEVISION APPARATUSFiled Jan. 6, 1928 Patented` .lune 13, 1933y s srrjss JOHN LOGIE BAIRD,OF LONDON, ENGLAND, ASSIGNOR OF `ONF-HALF TO TELEVISION LIMITED, OF,LONDON, ENGLAND, A BRITISH COMPANY ExrLonINc-i :DEVICE non'rELEvIsroivnrrAnATUs Application iled January 6, 1928, Serial No.244,964, and inv Great Britain January 21, 1927. l

This invention is for'im'provements in or relating to exploring devicesfor television apparatus, and has for its object to provide aconstruction of such device which will permit of the production ofbrighter images by the use of more than onesource of light for suchproduction, or will permit the reproduction of diEerent portions of thesame object simultaneously. f

According to this invention an exploring device for television apparatuscomprises a rotatable disc having mounted on it a plu` rality of sets oflight-transmitting devices whereof each set is arranged in a spiral orlike formation, and the devices of each set are arranged to receive andtransmit light all in the same direction, which direction is differentfrom that of the other sets.

The light-transmitting devices may be reflectors, or they may beconstituted by openings in the screen or by combinations of reflectorsand openings.

In one form, the invention comprises a rotatable disc having two or morespiral sets of holes formed in it','and a plurality ofinternally-reflecting rods or tubes whereof one terminates at each hole,said rods or tubes being so disposed that their other ends all sweepalong the same or substantially the same path in the rotation of thedisc.

In a modification of this invention, it comprises the combination with arotatable disc formed with two or more sets of spirallyarranged holes init, of two or more sets of mirrors, each mirror mounted adjacent a hole,the mirrors of each set being disposed similarly to one another, butwith the dispositions of the mirrors of the different sets differentfrom one another.

Either of the above described arrangements may be modifiedy by omittingthe refleeting devices for oneof the spiral sets of holes, or in yetanother modification, a set of spirally-arranged mirrors may be mountedon the disc and used instead of holes therein. Y

In the accompanying drawing, which illustrates diagrammatically variousembodiments of this invention- Figure 1 is a front elevation, and vspiral.

Figure 2 is a section on the line'2-2 of Figure 1, but drawn to a largerscale;

figure 3 showsk the front elevation of a modified construction;

Figure 4i is a section on the line 4-4 of Figure 3, but drawn to alarger scale; and

Figure 5 is a modification showing a combination of reflecting membersand apertures. Like reference, characters indicate like partsthroughoutthe drawing. f

Referring first to the construction illustrated in Figures 1 and 2, theexploring device comprises a disc 10 having a spirallyarranged set ofholes, the set being indicated as starting at 11 and extendingcompletely round the disc and terminating at 12. The

second similar spiral set of holes commences at the hole indicated bythe reference 13 and terminates at 14. VAs shown, the two spirals arecoterminous, each exploring one half of an area indicated at 15.

4Each of the holes of theouter spiral 11, 12, has a small mirror 16associated with it, and these mirrors are arranged as shown in Figure 2,at an angle of, say, 45 to the plane of the disc, with the reflectingface directed radially outwards. Figure 2 also indicates the positionofthe mirror 17 for the last hole 12 of the spiral 11, 12.

When vthis construction of device is used for a television receiver, alamp 18, whereof the brilliance is modulated in accordance with thereceived signals, is arranged to one side j Figure 2' is of sufiicientwidth in that plane I' to cover all the mirrors 16 to 17, in the outerThe inclination of the beam 19 and the mirrors 16, 17 is such that themirrors reflect the beam through their corresponding holes normally tothe surface of the disc 10, for example on to the screen whereon thereceived image is constituted and viewed.

The second or'inner spiral 13, 14 is provided witha similar set ofmirrors 20, 21,

but these mirrors are directed radially inf,"

The i Cil wards (as compared with those of the outer spiral beingdirected radially outwards) s0 that they receive light from a secondlamp 22.

It will be seen that with this arrangement each of the lamps 18, 22 isused in conjunction with only one of the spirals of holes, and cannotproduce any image by means of the spiral allocated to the other lamp.

The two spirals may be arranged inany desired manner; instead of eachcovering half the eld, each might cover the whole field, if so desired,so as to produce a picture of greater brilliancy, or each may cover aportion ofthe field, with the two portions overlapping tol produce agreater brilliancy7 of picture on the overlapping portionsA wherein thecenter of interest in the picture lies. Obviously, of course, any otherdisposition and' arrangement of lamps may be used with appropriatesettings of the mirrors, and more thanl two spirals may be used, eachwith its own lamp, if so desired.

In the construction diagrammatically illustrated in Figures 3 and 4, thedisc 23 is provided with two spirals of holes, indicated at 24, 25respectively, and with each ofthe holes there is associated aninternally reflecting tube or rod as shown at 26. Each tube or rod is-soshaped that one end of it, 27, terminates at the corresponding hole sothat abeam of light within it passes out through the hole in the disc,and its other end 28 is so situated as to pass in proximity to the lampduring the rotation of the disc, and receive the beam of lighttherefrom. As shown most clearly inf Figure 4, this construction andarrangement of reflecting devices permits the two lamps to be setside-by-side whilst confining the beam from each of them to its ownparticular spiral of holes.

The members 26 may be of quartz or like transparent material,transmitting the light lengthwise through them by total internalreflection, or they may be of tubular construction, for example opaque,provided with anl internal reflecting surface. Y

The members 26 for a spiral may be all of the same shape and size, asillustrated, A suitable selection of the width of the beam 29 (seeFigure 4) may be necessitated if the free ends of the tubes or rods arenot parallel with the plane of the disc, or if they are paralleltherewith, the width of the beam as at 30 need be only sufficient tocover the ends of the members.

Figure 5 illustrates yet another modification in which the spiral setsof light-transmitting elements on a rotatable disc 31 are constituted bya spiral of holes 32 and a spiral of` mirrors 33, these mirrors beingset on that side of the disc which is viewed by the observer, from apoint 34; in this case the spiral of holes 32 will be allotted to a lamp35 situated behind the disc 31, and the spiral of mirrors 33 will beallotted to a lamp 36 which is situated in front of the disc, the mir'-rors being so arranged as to reflect a beam of light from this lamptowards the observer.

l/Vhilst various specific constructions and arrangements of devices havebeen described, it is to be understood that the invention is not limitedin this manner, for various modifications may be made. Thus, forexample,

variousA combinations ofthe diflerentv light'- transmitting' deviceshereinbefore described may be made with oney another, as by usingmirrors like thoseof'Figure 1 for one spiral and internally-reflectingktubesor rods as in Figures 3 and 4" for another spiral, or the tubesandv rods on one spiral may be used in conjunction with open holes as inFigure, or twosets of mirrors arranged like the mirrors 33 in Figure 5may be used, the two sets being. oppositely directed. It will beappreciated that when mirrors on the front of the disc are used it isdesirable that the disc itself shouldbe of a non-reecting preferablydull black surface.

This invention has been described in vari- Y vous forms for use in thereceiving apparatus of a` televisionl system, but it can also be appliedto the exploring device used at the transmitting station. In a preferredform for use at a transmitting station, the explorsponding to those ofthe lamps above menti'onedl so that each cell co-operates with a singlespiral of the exploring device.V

When plain mirrors are used in the apparatus above described, these maybe replaced by concave mirrors which will thereby serve the doublepurpose of transmitting the light in the required direction and formingan image which is projected on the lightsensitive cell.

I claim l. An' exploring device comprising a rotatable element, and aplurality of series of spirally arranged light transmitting meansthereon, each light transmitting means including a reiiecting device,the refiecting devices inl each series being similarly disposed yandthose in different series being differently disposed.

2. In image producing apparatus, the

combination with a rotatable disc, of a pluelectro-optical energyconverting devices,`

said scanning elements being adapted to be interposed between saiddevices and an image or object and serving to transmit light beamstherebetween, the angular disposition of the elements being such thateach group is operatively associated with a different device and withone device only.

In testimony whereof I aHiX my signature.

JOHN LOGIE BAIRD.

